Transmission polarizer

ABSTRACT

The invention relates to a device for changing the polarization of an incident electromagnetic wave. Existing devices to change the polarization of an incident electromagnetic wave preserve signal decoupling, i.e., the relation between useful polarization and cross-polarization of the incoming signal. Furthermore, known prior art devices are far too big for many applications. The aim of the inventive device is to improve signal decoupling. During transmission of an electromagnetic wave through the transmission polarizer, the cross-coupled fraction of an incoming signal is greatly reflected thus leading to improved decoupling of the transmitted signal. Furthermore, the transmission polarizer can be manufactured in the form of a single planar printed board. The transmission polarizer is particularly useful to change the polarization of an incident electromagnetic wave, i.e. from linear to circular polarization or vice versa, and to rotate the polarization of an incident electromagnetic wave around a fixed angle.

BACKGROUND OF THE INVENTION

The invention relates to device for changing the polarization of anincident electromagnetic wave.

The concept of changing the polarization of an incident electromagneticwave can have various meanings. For example, it can be understood to bethe conversion of linear polarization into circular polarization or viceversa, or also a rotation of the polarization direction of the incidentelectromagnetic wave.

The deliberate changing of the polarization of electromagnetic waves isused in many application fields for increasing signal quality. Forexample, in radar technology, circular polarization is used to suppressrain echoes and thus increases the range of radar in the event of badweather. In a similar manner, in radio communication at frequencies inthe microwave range, circular polarization permits the reduction ofso-called inter-symbol interferences.

Interferences of this kind are produced when electromagnetic signals arereflected against objects on the way from the transmitter to thereceiver. When an electromagnetic wave is reflected, its polarizationchanges. In the extreme instance of a circularly polarized waveperpendicularly striking a flat reflector, the reflected wave maintainsthe rotational direction in space, but the propagation direction inspace is reversed so that, for example a right-handed circular polarizedwave becomes a left-handed circular polarized wave. Therefore an antennadesigned for right-handed circular polarization cannot receive thereflected, left-handed circular polarized signal so that the interferingsignal does not appear in the receiver. Correspondingly, interferingsignals whose polarization direction has not been completely reversed ina reflection are muted.

One conventional device for changing the polarization of an incidentelectromagnetic wave, for example, is the meander-line polarizer knownfrom the literature [Derek McNamara “An Octave Bandwidth Meander-LinePolarizer Consisting of Five Identical Sheets”, IEEE—APS 1981, Vol. 1,pp. 237-240]. This has the following features:

five dielectric printed circuit boards, which are embodied as planar andare disposed one behind the other, flat side to flat side,

on the front side, the printed circuit boards have a number ofelectrically conductive lines that are disposed in a preferreddirection,

an individual line is meander-shaped and extends over the cross sectionof a printed circuit board,

the meander-shaped lines on all of the printed circuit boards arealigned parallel, i.e. the two main axes of a meander-shaped line on aprinted circuit board, which are disposed in the plane of the front sideof the printed circuit board, and the two main axes of a meander-shapedline on another printed circuit board, which are disposed in the planeof the front side of the printed circuit board, do not differ from oneanother.

In particular, the multilayer structure of a meander-line polarizer madeup of a number of layered printed circuit boards disposed one behind theother necessitates its comparatively large spatial breadth, whichimpedes the use of this polarizer in many application fields, if notactually preventing it.

With a suitable dimensioning of a meander-line polarizer, an incidentelectromagnetic wave with linear polarization in a direction A isconverted into an electromagnetic wave with circular polarization in arotation direction B. A second incident electromagnetic wave with apolarization perpendicular to this (cross-polarization), i.e. withlinear polarization in a direction A′ perpendicular to the direction A,is converted into an electromagnetic wave with circular polarization ina rotation direction B′ opposite from the rotation direction B. Thismeans that the decoupling of a signal, i.e. the relationship betweenuseful polarization and cross-polarization, or the relationship betweenright-handed and left-handed circular polarization, cannot be improvedby means of a meander-line polarizer.

SUMMARY OF THE INVENTION

The object of the current invention, therefore, is to disclose a devicefor changing the polarization of an incident electromagnetic wave, whichimproves the decoupling of a signal.

With regard to the device for changing the polarization of an incidentelectromagnetic wave, the object is attained according to the inventionby virtue of the fact that the device

has at least one dielectric printed circuit board, which is embodied asplanar,

the at least one printed circuit board has a multitude of homogeneouslydistributed strip conductor structures on both its front side and itsback side,

the at least one printed circuit board is composed of elementary cells,which are each comprised of a strip conductor structure on the frontside of the printed circuit board, a strip conductor structure disposedopposite it on the back side of the printed circuit board, and thesubstrate of the printed circuit board disposed between the two stripconductor structures,

in each elementary cell, the two strip conductor structures are disposedin such a way that the two main axes of a strip conductor structure onthe front side of the printed circuit board, which are disposed in theplane of the front side, and the two main axes of a strip conductorstructure on the back side of the printed circuit board, which aredisposed in the plane of the back side, are respectively rotated inrelation to one another by a predetermined angle.

A conspicuous optical difference between the known meander-linepolarizer and a typical embodiment of the invention is comprised in thatin the first, a single element—an elongated meander-line—extends overthe entire cross section of a printed circuit board, while in thesecond, a multitude of elements—elementary cells or strip conductorstructures—are disposed in rows that extend over the cross section ofthe printed circuit board.

A first advantage of the invention over the meander-line polarizer iscomprised in that the desired changing of the polarization of anincident electromagnetic wave according to the invention can be achievedby means of a single printed circuit board and consequently, the spatialdimensions of a typical embodiment of the invention are significantlysmaller than those of a meander-line polarizer, which distinctlyincreases the number of potential fields in which it can be used incomparison to the latter.

Primarily, though, the device according to the invention has functionaldifferences in relation to a meander-line polarizer, by means of whichthe main advantage—a high degree of signal decoupling—can be achieved:

An incident electromagnetic wave with a particular polarization, forexample an electromagnetic wave with linear polarization in a directionA, which strikes the device according to the invention undergoes achange in its polarization, for example into an electromagnetic wavewith circular polarization in a rotation direction B. A second incidentelectromagnetic wave with a polarization that is perpendicular to thatof the first wave (cross-polarization) is reflected to the greatestdegree possible. This means that the decoupling of a signal, i.e. therelationship between useful polarization and cross-polarization, afterthe transmission of the signal through the device according to theinvention, is decisively improved by means of the reflection of thecross-polarized portion.

Improvements in the decoupling of a signal after its transmission whichgo beyond this, can be achieved by means of embodiments of the inventiondescribed below, whose features contribute to the improvement bothindividually and in combination.

One advantageous embodiment of the invention is comprised in that

each individual strip conductor structure on the front side of theprinted circuit board has different geometries in the direction of itstwo main axes, which are disposed in the plane of the front side, and/or

each individual strip conductor structure on the back side of theprinted circuit board has different geometries in the direction of itstwo main axes, which are disposed in the plane of the back side.

These different geometries of the strip conductor structures can, forexample, be produced in the form of rectangles, crosses, or ellipses.The advantages of such forms are comprised in their particularly highdegree of decoupling of a signal after its transmission through theprinted circuit board.

In another advantageous embodiment of the invention, in each elementarycell, the strip conductor structure on the front side of the printedcircuit board and the strip conductor structure on the back side of theprinted circuit board are disposed in such a way that

the projections of the circumscribed polygons of the strip conductorstructures of both sides of the printed circuit board onto the plane ofthe front side of the printed circuit board intersect one another.

Here and in the following, projection is understood to mean theperpendicular projection of coordinates with reference to the plane ofthe front side of the printed circuit board. A suitable coordinatesystem is established for example by the main axes of the stripconductor structure on the front side of the printed circuit board. Theconcept of the circumscribing polygon primarily relates to stripconductor structures in the form of crosses or similar forms, andsignifies a shortening of the edge contour as well as an enlargement ofthe enclosed area, for example in such a way that a cross iscircumscribed by a trapezoid or rectangle. For an elementary cell, whichcontains two strip conductor structures in the form of crosses, thefulfillment of the above-mentioned disposition requirement does nottherefore absolutely mean that the projections of the strip conductorstructures themselves also intersect.

However if this is the case, then a further improvement of thedecoupling gradient can be produced as a result. Accordingly, in a moreadvantageous embodiment of the invention, the strip conductor structureon the front side of the printed circuit board and the strip conductorstructure on the back side of the printed circuit board are disposed insuch a way that

the projections of the strip conductor structures of both sides of theprinted circuit board onto the plane of the front side of the printedcircuit board intersect one another.

Another improvement of the decoupling gradient can be achieved with anideal, central intersection of the projections of the strip conductorstructures. Accordingly, in a more advantageous embodiment of theinvention, the strip conductor structure on the front side of theprinted circuit board and the strip conductor structure on the back sideof the printed circuit board are disposed in such a way that

the projection of the intersecting point of the main axes of the stripconductor structure of the front side of the printed circuit board ontothe plane of the front side of the printed circuit board coincides withthe projection of the intersecting point of the main axes of the stripconductor structure of the back side of the printed circuit board ontothe plane of the front side of the printed circuit board.

In additional advantageous embodiments of the invention,

all of the strip conductor structures of at least one side of at leastone printed circuit board have the same form and the same dimensions,and/or

all of the strip conductor structures of at least one side of at leastone printed circuit board have uniform distances from one another in atleast one preferred direction.

In additional advantageous embodiments of the invention,

the individual strip conductor structures of each side of a printedcircuit board are aligned parallel to one another, and

the individual strip conductor structures of each side of a printedcircuit board are disposed symmetrically in relation to at least oneaxis disposed in the planar surface of the printed circuit board,preferably disposed in such a way that

the individual strip conductor structures of each side of a printedcircuit board are disposed collinearly in rows that extendperpendicularly to each other, or

the individual strip conductor structures of each side of a printedcircuit board are disposed in a radially symmetrical manner.

The collinear disposition of the strip conductor structures in rows thatextend perpendicularly to one another can be conceived of has ahomogenous filling of a rectangular pattern on the printed circuit boardwith strip conductor structures.

In another advantageous embodiment of the invention, this contains

a number of dielectric printed circuit boards, which are embodied asplanar and are disposed with their flat sides parallel to one another,one behind the other, preferably in a congruent fashion.

BRIEF DESCRIPTION OF THE DRAWINGS

Exemplary embodiments of the device according to the invention will beexplained in detail below in conjunction with FIGS. 1 and 2.

FIG. 1 shows the principal operation of the device according to theinvention.

FIG. 2 shows an elementary cell of the printed circuit board accordingto FIG. 1.

DETAILED DESCRIPTION OF THE INVENTION

FIG. 1 shows the principal operation of the device according to theinvention, here in conjunction with the particular embodiment of aplanar, dielectric printed circuit board 1, which after the transmissionof an incident electromagnetic wave 3, which is linearly polarized inthe y direction, converts it into a circularly polarized electromagneticwave 4. The field intensity vectors in the x and y direction are labeledEx and Ey.

On both its front side 11 and its back side 12, the printed circuitboard 1 has a multitude of homogeneously distributed strip conductorstructures 21, 22. The printed circuit board 1 is made up of elementarycells 2, which are each comprised of a strip conductor structure 21 onthe front side 11 of the printed circuit board 1, a strip conductorstructure 22 disposed opposite from it on the back side 12 of theprinted circuit board 1, and the substrate of the printed circuit board1 disposed between the two strip conductor structures 21, 22. It shouldbe noted that the strip conductor structures 22 disposed on the backside 12 are not shown in correct perspective in FIG. 1, but that thedashed lines respectively describe their projections onto the front side11!

In each elementary cell 2, the two strip conductor structures 21, 22 aredisposed in such a way that the two main axes of a strip conductorstructure 21 on the front side 11 of the printed circuit board 1, whichare disposed in the plane of the front side 11, and the two main axes ofa conductor strip structure 22 on the back side 12 of the printedcircuit board 1, which are disposed in the plane of the back side 12 ofthe printed circuit board 1, are respectively offset from each other bya predetermined angle.

An individual strip conductor structure 21 on the front side 11 of theprinted circuit board 1 has different geometries in the direction of itstwo main axes disposed in the plane of the front side 11. Likewise, anindividual strip conductor structure 22 on the back side 12 of theprinted circuit board 1 has different geometries in the direction of itstwo main axes disposed in the plane of the back side 12. In both cases,these different geometries are produced by the embodiment of the stripconductor structures 21, 22 in the form of rectangles.

In each elementary cell 2, the strip conductor structure 21 on the frontside 11 of printed circuit board 1 and the strip conductor structure 22on the back side 12 of printed circuit board 1 are disposed in such away that the projection of the intersecting point of the main axes ofthe strip conductor structure 21 of the front side 11 of the printedcircuit board 1 onto the plane of the front side 11 of the printedcircuit board 1 coincides with the projection of the intersecting pointof the main axes of the strip conductor structure 22 of the back side 12of the printed circuit board 1 onto the plane of the front side 11 ofthe printed circuit board 1. This means that the strip conductorstructures 21, 22 are disposed in such a way that in this instance, thecenters of the two rectangles are disposed one above the other.

All of the conductor strip structures 21, 22 of one side 11, 12 of theprinted circuit board 1 have the same form and the same dimensions,namely of a respectively identical rectangle. All of the conductor stripstructures 21, 22 of one side 11, 12 of the printed circuit board 1 haveuniform distances in relation to one another in two preferreddirections, in this instance in the horizontal and vertical direction inthe planar surface of the printed circuit board 1.

The individual strip conductor structures 21, 22 of each side 11, 12 ofthe printed circuit board 1 are aligned parallel to one another. Inaddition, the individual strip conductor structures 21, 22 of each side11, 12 of the printed circuit board 1 are disposed symmetrically inrelation to two axes in the planar surface of the printed circuit board1. In this instance, on the front side 11 of the printed circuit board1, these are the vertical and horizontal axis through the center point,and on the back side 12 of the printed circuit board 1, these are twoaxes through the center point, which are respectively rotated out of thevertical and the horizontal by the same angle around the center point.Furthermore, the individual strip conductor structures 21, 22 of arespective side 11, 12 of the printed circuit board 1 are disposedcollinearly in rows that extend perpendicularly to one another, and therows that extend perpendicularly to one another on one side 11, 12 ofthe printed circuit board 1 respectively intersect at the center of astrip conductor structure 21, 22.

FIGS. 2 a and 2 b depict in detail a preferred embodiment of anelementary cell 2 of the device according to the invention, inaccordance with FIG. 1. FIG. 2 a shows a projection onto the flat sideof the printed circuit board 1 according to FIG. 1, FIG. 2 b shows asection through the printed circuit board 1 according to FIG. 1. Theterm elementary cell 2 is understood to mean a) a strip conductorstructure 21 of the front side 11 of the printed circuit board 1, b) thesubstrate of the printed circuit board 1 disposed underneath it, whichhas the thickness h and the permittivity εr, and c) the second stripconductor structure 22, which is disposed on the back side 12 of theprinted circuit board 1 and is rotated in relation to the first by theangle π.

In the exemplary embodiment shown in FIGS. 2 a and 2 b, the stripconductor structure 21 has the form a rectangle R1 with the differentside lengths a1 and b1, and the strip conductor structure 22 has theform of the rectangle R2 with the different side lengths a2 and b2. Bymeans of the different side lengths, the rectangles R1, R2 fulfill therequirement for different geometries in the direction of theirrespective two main axes x, y and ξ, ψ, which are disposed parallel tothe plane of the front side 11 of the printed circuit board 1.

In the elementary cell 2, the strip conductor structure 21 on the frontside 11 of the printed circuit board 1 and the strip conductor structure22 on the back side 12 of the printed circuit board 1 are disposed insuch a way that the projection of the intersecting point of the mainaxes x, y of the strip conductor structure 21 of the front side 11 ofthe printed circuit board 1 onto the plane of the front side 11 of theprinted circuit board 1 coincides with the projection of theintersecting point of the main axes ξ, ψ, of the strip conductorstructure 22 of the back side 12 of the printed circuit board 1 onto theplane of the front side 11 of the printed circuit board 1. This meansthat the strip conductor structures 21, 22 are disposed in such a waythat in this instance, the respective centers of the two rectangles aredisposed one above the other.

All of the strip conductor structures 21, 22 on both sides 11, 12 of theprinted circuit board 1 have uniform average distances from one anotherin two preferred directions, which clearly determine their dispositionon the printed circuit board 1. In this instance, the preferreddirections are the x and y direction of the x-y coordinate system of thestrip conductor structure 21. In the exemplary embodiment shown in FIG.1, these directions correspond to the vertical and horizontal of theprinted circuit board 1. The average distances from a strip conductorstructure 21 to its respective four neighboring strip conductorstructures 21 define the dimensions of an elementary cell 2. The averagedistance of two strip conductor structures 21 in the lateral directionof the front side 11 of the printed circuit board 1 (or in the xdirection of the x-y coordinate system of the strip conductor structure21 depicted) is labeled A in FIG. 2 a. The average distance of two stripconductor structures in the longitudinal direction of the front side 11of the printed circuit board 1 (or in the y direction of the x-ycoordinate system of the strip conductor structure 21 depicted) islabeled B as shown in and FIG. 2 a.

An optimal dimensioning of a printed circuit board 1 (with regard to theform R1, R2 and the dimensions a1, b1, a2, b2 of the strip conductorstructures 21, 22; the distances A, B of the strip conductor structures21, 22 of a printed circuit board side 11, 12 in relation to oneanother; the angle π by which the strip conductor structures 21, 22 oftwo printed circuit board sides 11, 12 are rotated in relation to eachother; the thickness h and the permittivity Er of the printed circuitboard substrate) is suitably constructed by means of the field theorycalculations. Evolutions for the field intensities in the air and in thedielectric are determined here; the coefficients of these fieldintensities are calculated by means of the edge conditions anduniformity conditions on the metal and dielectric surfaces.

For example, for a device for changing the polarization of an incidentelectromagnetic wave with a frequency of 30 Gigahertz from linearpolarization into circular polarization, the following optimizeddimensioning results:

signal frequency 30 GHz number of printed circuit boards 1 form of stripconductor structures identical rectangles R1 on the front side 11,identical rectangles R2 on the back side 12 dimensions of stripconductor structures a1 = 3.35 mm b1 = 1.65 mm a2 = 0.50 b2 = 3.05 mmdisposition of strip conductor structures rows perpendicular to oneanother A = 4.0 mm B = 5.2 mm rotation of strip conductor structures ι =33° thickness of printed circuit board substrate h = 1.57 mmpermittivity of printed circuit board substrate εr = 2.33

Correspondingly, in a second example for a device for changing thepolarization of an incident electromagnetic wave with a frequency of 35Gigahertz from linear polarization to circular polarization, thefollowing optimized dimensioning results:

signal frequency 35 GHz number of printed circuit boards 1 form of stripconductor structures identical rectangles R1 on the front side 11,identical rectangles R2 on the back side 12 dimensions of stripconductor structures a1 = 2.76 mm b1 = 1.38 mm a2 = 0.30 b2 = 2.58 mmdisposition of strip conductor structures rows perpendicular to oneanother A = 4.74 mm B = 3.01 mm rotation of strip conductor structures ι= 32° thickness of printed circuit board substrate h = 1.52 mmpermittivity of printed circuit board substrate εr = 2.5

In the embodiments of these two examples, the device according to theinvention turns out to be particularly suited for changing thepolarization of incident electromagnetic waves with frequencies of 30 or35 Gigahertz from linear polarization into circular polarization andtherefore is suited for a use in radar technology, for example.

However, the invention is not limited to only the exemplary embodimentsdescribed, but can instead be transferred elsewhere.

For example, instead of the polarization change in the form of apolarization conversion from linear polarization into circularpolarization or vice versa, it is conceivable to carry out apolarization change in the form of a rotation of the polarization forexample by 90 degrees.

Potential uses for a device of this kind for rotating the polarizationof an incident electromagnetic wave generally lie in the field ofconvoluted lenses or reflector structures, particularly in theproduction of a so-called fan beam (i.e. an antenna radiation, which hasan intense beam in one direction, but has a weak beam or no beam at allin the other direction) with the aid of a special wave guide. A deviceof this kind is easy to develop if the electrical field is intended tobe disposed in the direction of the large lobe width (so-called Flat Hhorn). There is a problem when the field is intended to be disposed inthe other direction (so-called flat E horn).

With the aid of the device according to the invention, which rotates thefield by 90 degrees, though, a Flat H horn can now be used and thedevice for rotation can be employed.

Furthermore it is possible to change the uniform dimensions and/orrectangular forms of the strip conductor structures. As a result, stripconductor structures with different forms and dimensions can easily alsooccur, for example, on different printed circuit boards or on differentsides of a printed circuit board or in different rows on one side of aprinted circuit board or alternatingly within one row or in a differentarrangement.

In the exemplary embodiments shown, the rectangular strip conductorstructures are arranged so that they form the rows that are parallel toone another and perpendicular to one another, wherein the rows thatextend perpendicularly to one another respectively intersect in thecenter of a strip conductor structure. However, it is easily conceivablefor the rows which are parallel to each other to be offset from eachother so that the rows that extend perpendicularly to each other nolonger intersect in the center of one strip conductor structure, but inthe center of four respective strip conductor structures, i.e. at theintersecting point or contacting point of four respective elementarycells. Furthermore, instead of the axially symmetrical disposition ofthe strip conductor structures, it is conceivable to use a radiallysymmetrical disposition of them.

Moreover, it is conceivable to dispose a number of printed circuitboards one behind the other in the beam direction.

What is claimed is:
 1. A device for changing the polarization of anincident electromagnetic wave comprising: a planar dielectric printedcircuit board with a front side, a substrate and a back side; and aplurality of homogeneously distributed strip conductor structuresdisposed on the front and back sides of the printed circuit board wherethe printed circuit board is composed of an array of elementary cells,each elementary cell including one said strip conductor structure on thefront side of the printed circuit board, one said strip conductorstructure on the back side of the printed circuit board which isdisposed opposite the one said front side strip conductor structure andthe substrate of the printed circuit board between the one said frontand one said back side strip conductor structures; wherein, each frontside strip conductor structure has two main axes (x, y) disposed in aplane on the front side of the printed circuit board, each back sidestrip conductor structure has two main axes (ξ, ψ) disposed in a planeon the back side of the printed circuit board, and, in each elementarycell, the respective main axes of the one said front and one said backside strip conductor structures are angled relative to one another by apredetermined angle greater than zero.
 2. The device according to claim1, wherein at least one of each individual strip conductor structure onthe front side of the printed circuit board has a different geometry ineach direction of the two main axes (x, y), and each individual stripconductor structure on the back side of the printed circuit board has adifferent geometry in each direction of the two main axes (ξ, ψ).
 3. Thedevice according to claim 2, wherein the front and back side stripconductor structures have the form of one of rectangles, crosses andellipses.
 4. The device according to claim 1, wherein, in eachelementary cell, if the one said front and one said back side stripconductor structures are circumscribed by polygons, the front and backstrip conductor structures are disposed in such a way that projectionsof the circumscribed polygons onto the plane of the front side of theprinted circuit board intersect one another.
 5. The device according toclaim 1, wherein, in each elementary cell, the one said front and onesaid back side strip conductors are disposed in such a way thatprojections of the front and back side strip conductors onto the planeof the front side of the printed circuit board intersect one another. 6.The device according to claim 5, wherein, in each elementary cell, theprojection of the intersecting point of the main axes (x, y) of thestrip conductor structure of the front side of the printed circuit boardonto the plane of the front side of the printed circuit board coincideswith the projection of the intersecting point of the main axes (ξ, ψ) ofthe strip conductor structure of the back side of the printed circuitboard onto the plane of the front side of the printed circuit board. 7.The device according to claim 1, wherein at least one of: all of thestrip conductor structures of at least one side of the printed circuitboard have the same form and the same dimensions; and all of stripconductor structures of at least one side of the printed circuit boardhave uniform distances from one another in at least one direction. 8.The device according to claim 1 wherein the individual strip conductorstructures of each side of the printed circuit board are alignedparallel to one another, and the individual strip conductor structuresof each side of the printed circuit board are disposed symmetrically inrelation to at least one axis disposed in the planar surface of theprinted circuit board.
 9. The device according to claim 8, wherein atleast one of the individual strip conductor structures of each side ofthe printed circuit board are disposed collaterally in rows that extendperpendicularly to each other, and the individual strip conductorstructures of each side of the printed circuit board are disposed in aradially symmetrical manner.
 10. The device according to claim 1,wherein the device includes a number of dielectric printed circuitboards each said printed circuit board being disposed with their flatsides parallel to one another, one behind the other.
 11. The deviceaccording to claim 10, wherein the printed circuit boards are disposedone behind the other in a congruent fashion.
 12. The device according toclaim 6, wherein the device has only one planar dielectric printedcircuit board, the individual strip conductor structures of each side ofthe printed circuit board are aligned parallel to one another, and theindividual strip conductor structures of each side of the printedcircuit board are disposed symmetrically in relation to at least twoaxes disposed in the planar surface of the printed circuit board in sucha way that the individual strip conductor structures of each side of theprinted circuit board are disposed collinearly in rows that extendperpendicularly to one another, and that the rows that extendperpendicularly to one other on one side of the printed circuit boardrespectively intersect in the center of a strip conductor structure. 13.The device according to claim 12, wherein on the front side of theprinted circuit board, the strip conductor structures have the form ofrectangles (R1) which have approximate edge lengths of 3.35 mm and 1.65mm, on the back side of the printed circuit board, the strip conductorstructures have the form of rectangles (R2) which have approximate edgelengths of 0.50 mm and 3.05 mm, the rows of the front side stripconductor structures, which are disposed parallel to the first symmetryaxis of the front side of the printed circuit board, have an averagedistance (A) of approximately 4.0 mm, the rows of back side stripconductor structures, which are disposed parallel to the second symmetryaxis of the front of the printed circuit board, have an average distance(B) of approximately 5.2 mm, and in each elementary cell, the one saidfront and one said back side strip conductor structures are disposed insuch a way that the two main axes (x, y) of the front side stripconductor structure, which are disposed in the plane of the front sideof the printed circuit board, and the two main axes (ξ, ψ) of the backside strip conductor structure, which are disposed in the plane of theback side, are respectively angled in relation to one another by apredetermined angle that is approximately 33 degrees, the substrate ofthe printed circuit board having a thickness of approximately 1.57 mmand permittivity of approximately 2.33.
 14. The device according toclaim 8, wherein the front side strip conductor structures have the formof rectangles (R1) which have approximate edge lengths of 2.76 mm and1.38 mm, the back side strip conductor structures have the form ofrectangles (R2) which have approximate edge lengths of 0.30 mm and 2.58mm, the rows of front side strip conductor structures, which aredisposed parallel to the first symmetry axis of the front side of theprinted circuit board, have an average distance (A) of approximately4.74 mm, the rows of back side strip conductor structures, which aredisposed parallel to the second symmetry axis of the front side of theprinted circuit board, have an average distance (B) of approximately3.01 mm, and in each elementary cell, the one said front and one saidback side strip conductor structures are disposed in such a way that thetwo main axes (x, y) of the front side strip conductor structure, whichare disposed in the plane of the front side, and the two main axes (ξ,ψ) of the back side strip conductor structure, which are disposed in theplane of the back side, are respectively angled in relation to oneanother by an angle of approximately 32 degrees, the substrate of theprinted circuit board having a thickness of approximately 1.52 mm and apermittivity of approximately 2.5.
 15. A use of a device according toclaim 1 to change the polarization of an incident electromagnetic wavefrom linear polarization into circular polarization or vice versa.
 16. Ause of a device according claim 1 to rotate the polarization of anincident electromagnetic wave by a fixed angle.
 17. The use according toclaim 16, wherein the fixed angle is approximately 90 degrees.